Gunnar Peterson has long been known by celebrities and athletes as a no-BS trainer. Over the years, his client roster has included Jennifer Lopez, Sofia Vergara, a bevy of Kardashians, and the Los Angeles Lakers (to name just a few). But even his most high-profile clients have to put in work to see results from his training programs—and that doesn't just begin and end in his oft-Instagrammed gym.

When it comes to reaching a fitness goal—whether that’s building strength, losing weight, working toward a performance goal, or whatever else a person is striving toward—there's more to it than just showing up to workouts and going through the motions."[Even] if [a client is] with me six times a week, there's still an extra 162 or more hours left," Peterson tells SELF. How someone spends their time outside the gym can make all the difference in reaching their goals, the trainer says. And that’s true whether you’re one of Peterson’s celeb clients or not.

Whether you're not quite seeing the results you want from your workout routine or you're just ready to up your game, here are the four habits Peterson says everyone should adopt to get the most out of their fitness routines.

1. Get seven to nine hours of high-quality sleep each night.

Peterson, who is a brand ambassador for SleepScore Labs, is a major proponent of prioritizing sleep to optimize fitness results—and with good reason. Research suggests that getting enough sleep is crucial for muscle recovery.

According to an article published in the journal Medical Hypotheses, which reviewed 41 studies, hormones like testosterone and insulin-like growth factor are reduced under sleep-deprived conditions. These hormones play a major role in regulating and stimulating protein synthesis, which is the process that essentially grows and strengthens muscle fibers. In fact, the researchers suggest that the effect sleep deprivation has on hormones may actually contribute to protein degradation, which leads to muscle breakdown.

Plus, it's well known that sleep deprivation can lead to brain fog and delayed reaction time, which can be dangerous in the gym. "If you translate that to the weight room, [sleep deprivation can mean] not quite getting your form right, and your ability to follow cues and direction decreases," says Peterson. All of this can increase your risk of getting hurt, which is a quick way to derail your routine.

The good news? Adopting a healthy sleep routine can get your brain and body back on track. Plus, more sleep may also improve your actual performance in the gym (a small 2011 study on 11 collegiate basketball players even found that sprint time and shooting accuracy improved when they got more sleep).

While sleep needs differ from person to person, the National Sleep Foundation says most adults need seven to nine hours every night. (Just because you can “get by” on four or five hours doesn’t mean it’s a good thing to do regularly.)

2. Stay hydrated during your workouts (and all day long).

This is the second most important thing on Peterson's list. "The two [lifestyle factors] that are most overlooked are hydration and sleep," he says, “and to me, those are the two easiest to fix."

And it's worth fixing—every cell in your body needs water to function properly. When you exercise, you lose fluids via sweat, and not replenishing them may have a negative impact on your workout.

According to a review of nine studies on dehydration and athletic performance, research has found that working out in a dehydrated state reduces aerobic capacity (compared to a baseline hydrated state). Several of the studies they looked at found decreases in VO2 max, which is a measure of how efficient your body is at using oxygen, and some suggested dehydration may also increase your rate of perceived exertion, or how hard you think you're working. Other studies found dehydration can decrease speed and overall energy.

In general, there's no need to obsess over getting 8 cups a day—listen to your body and make sure you actually drink when you feel thirsty.

For his clients, Peterson recommends starting the day with a glass of water before anything else—it'll help you establish the habit. You can also keep water bottles around to remind you to sip during the day.

3. When it comes to eating habits, think quality, quantity, and timing.

Fueling your workouts with solid nutritional choices is important for making the most of your time in the gym. Peterson recommends stepping back and re-evaluating what actually works for you and what might just be a habit. "You've got to look at three things: quality, quantity, and timing," he says. Once you figure out where you could improve, you can start to make little tweaks to optimize your nutrition—no need to overhaul everything at once.

Quality refers to the type of foods you're eating: Maybe you could work on incorporating more whole foods (like nutrient-packed vegetables), cutting down on added sugar, or upping your protein intake. Quantity means looking at if you’re mindlessly snacking on more than your body needs, or if you're not eating enough to fuel your workouts. Timing doesn't mean that outdated "don't eat after 7 P.M." rule—it means remembering to eat regularly throughout the day so you’re not ravenous by the time you get home at night and end up making poor nutritional choices.

Establishing good nutrition habits is important for your fitness routine because over time, not-so-good eating habits can impede results—whether your goal is to get stronger, lose weight, run a faster 5k, or anything in between.

If you're not consuming enough carbohydrates and protein, you may be impacting your body's ability to perform well during your workouts and recover properly afterward: Carbohydrates help replenish the glycogen stored in your muscles, which your body uses for energy during a workout. Protein is broken down into the amino acids that your body uses to rebuild muscle fibers so that they can recover stronger and larger than before.

While nutritional needs vary, the U.S. Dietary Guidelines say 45 to 65 percent of your daily calories should come from carbohydrates, 20 to 35 percent should come from fat, and 10 to 35 percent should come from protein. Endurance athletes usually need more carbs to properly fuel for training and races.

4. Hold yourself accountable in the gym to make sure you're not coasting through workouts.

Yes, sometimes getting to the gym is half the battle, but once you're there, it's important to make sure you're actually focused. "[My clients] can't phone it in with me," says Peterson. "I'll call you on it."

While we can't all have a tough-love trainer like Peterson pushing us along, there are some questions he says you can ask yourself to check in every once in a while. "Are you doing the same workout all the time? Are you phoning it in on your elliptical at home? Are you taking the same class and phoning it in from an intensity standpoint? Maybe it's time to shake that up," he says.

The problem with doing the same workout over and over is that bodies are smart—over time, your muscles adapt to doing the same moves with the same weight at the same intensity. Once your body gets comfortable, you’ll stop seeing results from the same workouts. Routines are great, and they can help you stay consistent, but it's also important to keep mixing it up in some way to keep challenging your body.

If you’re doing the same things day in and day out, consider challenging yourself with something new, whether that's trying a new class or pushing yourself a little harder (if you are comfortable enough with your workout to up the intensity safely). Always log the same number of miles on the treadmill? Try an interval routine that feels harder to you. Know your yoga flow by heart? Try a barre class.

Overall, the key is to be honest with yourself about how you can be making the time you log in the gym count even more. Sometimes, re-evaluating just one thing can be a game-changer in taking your workouts to the next level.